Solid ink or phase change ink printers conventionally receive ink in a solid form, either as pellets or as ink sticks. The solid ink pellets or ink sticks are typically placed in an “ink loader” that is adjacent to a feed chute or channel. A feed mechanism moves the solid ink sticks from the ink loader into the feed chute and channel and then urges the ink sticks through the feed channel to a heater assembly where the ink is melted. In some solid ink printers, gravity pulls solid ink sticks through the feed channel to the heater assembly. Typically, a heater plate (“melt plate”) in the heater assembly melts the solid ink impinging on it into a liquid that is delivered to a print head for jetting onto a recording medium. U.S. Pat. No. 5,734,402 for a Solid Ink Feed System, issued Mar. 31, 1998 to Rousseau et al.; and U.S. Pat. No. 5,861,903 for an Ink Feed System, issued Jan. 19, 1999 to Crawford et al., the disclosures of which are incorporated herein by reference, describe exemplary systems for using solid ink sticks (“phase change ink sticks”) in a phase change ink printer.
FIG. 1 is a perspective view of a prior art phase change ink printer 110 having a solid ink feed system as described in the Crawford patent noted above. Printer 110 includes an outer housing having a top surface 112 and side surfaces 114. A user interface display, such as a front panel display screen 116, displays information concerning the status of the printer, and user instructions. Buttons 118 or other control actuators for controlling operation of the printer are adjacent the user interface window, or may be at other locations on the printer. An ink jet printing mechanism (not shown) is contained inside the housing. Such a printing mechanism is described in U.S. Pat. No. 5,805,191, entitled Surface Application System, to Jones et al, and U.S. Pat. No. 5,455,604, entitled Ink Jet Printer Architecture and Method, to Adams et al, the disclosures of which are incorporated herein by reference. The top surface of the housing includes a hinged ink access cover 120 that opens (see FIG. 2) to provide the user access to an ink feed system contained under the top surface of the printer housing that delivers ink to the printing mechanism.
FIG. 2 is a partial top perspective view of the prior art phase change ink printer 110 with its ink access cover 120 open. As at least partially discernable in FIG. 2, the ink access cover 120 is attached to an ink load link 122 so that when the ink access cover 120 is raised, the ink load link 122 slides and pivots to an ink load position. The interaction of the ink access cover 120 and the ink load link 122 is described in U.S. Pat. No. 5,861,903 for an Ink Feed System, which was noted above. Opening the ink access cover 120 reveals an insertion key plate 126 having keyed openings 124A-D. Each keyed opening 124A, 124B, 124C, 124D provides access to a feed key plate having respective keyed openings positioned at the insertion end(s) of respective individual feed channels 129A, 129B, 129C, 129D of the solid ink feed system. The prior art phase change ink printer 110 is configured to receive ink sticks inserted through the respective keyed openings 124A, 124B, 124C, 124D (as indicated generally by respective insertion direction arrows 131A, 131B, 131C, and 131D). A push block is coupled to the ink load link and is spring-biased to advance or feed the ink sticks through the respective feed channels 129A, 129B, 129C, 129D.
Ink loaders typically hold many ink sticks at once and each individual ink stick typically must travel several times its length to reach the melt plate. The wax-like components from which phase change ink sticks are typically made are typically designed to bond to media of many different types, and, accordingly, they may become slightly sticky in some environmental conditions. Consequently, some phase change ink printers occasionally encounter intermittent sticking and slipping of ink sticks in the ink loaders as the ink sticks are pushed through the ink loaders. Feed channel length and complexity of the feed path may also contribute to the intermittent sticking of ink sticks in the feed channel.
The cover and ink loader link configuration of the prior art printer requires the printer to have a rear loader for solid ink sticks and an ink melter at the front end of the printer. This configuration is compatible with print heads that are located below the front of the drip ink loaders. Open reservoirs into which melted ink drips are not necessary in systems that deliver melted ink from an ink melter to a print head through a conduit, such as the melting chambers shown in commonly assigned, co-pending U.S. patent application bearing Ser. No. 11/411,678, which is entitled “System And Method For Melting Solid Ink Sticks In A Phase Change Ink Printer” and which was filed on Apr. 26, 2006. These types of melting chambers enable the ink loader to be positioned in other locations to optimize the printer architecture. This flexibility would also enable a phase change ink printer to incorporate a scanner more easily so it could operate as a multi-function printer.
As emerging technologies reduce the time for generating solid ink images, faster solid ink delivery systems need to be developed. Increased feed speed, however, may increase the risk of intermittent sticking. Solid ink delivery systems that reduce the risk of intermittent sticking while enabling reduced liquid ink production times are desirable.